A Surgical Case of a Ciliated Muconodular Papillary Tumor That Required Additional Exploration to Distinguish It from Mucinous Adenocarcinoma in situ

Abstract

Background. Ciliated muconodular papillary tumor (CMPT), a novel benign tumor, often masquerades as adenocarcinoma in situ (AIS), as the tumor cells exhibit a lepidic growth pattern. Case. A 70-year-old female who underwent nephroureterectomy for ureteral cancer was referred to our department due to a subpleural pulmonary nodule detected on CT for surveillance of the ureteral cancer. The nodule was resected via wedge resection under video assistance. The initial pathological examination showed results suggestive of AIS. Further examinations revealed the nodule to be CMPT, with negative findings for a mutation in the KRAS gene. Conclusions. Preserving the basal epithelial lining facilitates the ability to make a correct diagnosis of CMPT. Peripheral CMPT is treated with wedge resection as the optimal procedure, while central CMPT can be treated with surgery.